1. Field of the Invention
The present invention pertains to the storage of information, and particularly to automated cartridge handling systems such as cartridge libraries which store cartridges or cassettes of magnetic tape.
2. Related Art and Other Considerations
In the early days of computers, information requiring storage could be transmitted from a computer to a tape drive, whereat the information was magnetically recorded on or read from a large reel of tape. Upon completion of an operation of recording on the tape, for example, the reel would be removed manually from the tape drive and mounted in a rack. Another reel from the rack could then be manually mounted, if necessary, in the drive for either an input (tape reading) or output (recording to tape) operation.
Eventually it became popular to enclose magnetic tape in a cartridge, the cartridge being considerably smaller than the traditional tape reels. While many persons are familiar with tape cartridges of a type which can be loaded into a xe2x80x9ctape deckxe2x80x9d for reproduction of audio information (e.g., music), it is not as commonly realized that similar cartridges, although of differing sizes, can be used to store such information as computer data. For years now magnetic tape cartridges have proven to be an efficient and effective medium for data storage, including but not limited to computer back-up.
Large computer systems have need to access numerous cartridges. To this end, automated cartridge handling systems or libraries for cartridges have been proposed for making the cartridges automatically available to the computer. Many of these automated libraries resemble jute boxes. Typically, prior art automated cartridge libraries have an array of storage positions for cartridges, one or more tape drives, and some type of automated changer or cartridge engagement/transport mechanism for picking or gripping a cartridge and moving the cartridge between a storage position and the tape drive.
Important to the automation of cartridge libraries as previously known has been the provision of the cartridge changer or cartridge engagement/transport mechanism for picking or gripping a cartridge and moving the cartridge between a storage position and the tape drive. Such robotic mechanisms, often called a cartridge xe2x80x9cpickerxe2x80x9d or xe2x80x9cgripperxe2x80x9d, is typically mounted in a library frame in order to introduce and remove cartridges relative to one or more stationary drives. The stationary drive and the picker are typically mounted to the same basic frame structure of the library.
The following United States patents and patent applications, all commonly assigned herewith and incorporated herein by reference, disclose various configurations of automated cartridge libraries, as well as subcomponents thereof (including cartridge engagement/transport mechanisms, entry/exit ports, and storage racks for housing cartridges):
U.S. Pat. No. 4,984,106 to Herger et al., entitled xe2x80x9cCARTRIDGE LIBRARY SYSTEM AND METHOD OF OPERATION THEREOFxe2x80x9d.
U.S. Pat. No. 4,972,277 to Sills et al., entitled xe2x80x9cCARTRIDGE TRANSPORT ASSEMBLY AND METHOD OF OPERATION THEREOFxe2x80x9d.
U.S. Pat. No. 5,059,772 to Younglove, entitled xe2x80x9cREADING METHOD AND APPARATUS FOR CARTRIDGE LIBRARYxe2x80x9d.
U.S. Pat. No. 5,103,986 to Marlowe, entitled xe2x80x9cCARTRIDGE RACKxe2x80x9d.
U.S. Pat. Nos. 5,237,467 and 5,416,653 to Marlowe, entitled xe2x80x9cCARTRIDGE HANDLING APPARATUS AND METHOD WITH MOTION-RESPONSIVE EJECTIONxe2x80x9d.
U.S. Pat. No. 5,498,116 to Woodruff et al., entitled xe2x80x9cENTRY-EXIT PORT FOR CARTRIDGE LIBRARYxe2x80x9d.
U.S. Pat. No. 5,487,579 to Woodruff et al., entitled xe2x80x9cPICKER MECHANISM FOR DATA CARTRIDGESxe2x80x9d.
U.S. Pat. No. 5,718,339 to Woodruff et al., entitled xe2x80x9cCARTRIDGE RACK AND LIBRARY FOR ENGAGING SAMExe2x80x9d.
U.S. Pat. No. 5,739,978, entitled xe2x80x9cCARTRIDGE HANDLING SYSTEM WITH MOVING I/O DRIVExe2x80x9d.
U.S. Pat. No. 6,008,964, entitled xe2x80x9cCARTRIDGE LIBRARY AND METHOD OF OPERATION THEREOFxe2x80x9d.
U.S. patent application Ser. No. 08/970,205, entitled xe2x80x9cCARTRIDGE LIBRARY WITH CARTRIDGE LOADER MOUNTED ON MOVABLE DRIVE ASSEMBLYxe2x80x9d.
U.S. patent application Ser. No. 09/121,541, entitled xe2x80x9cCARTRIDGE LIBRARY AND METHOD OF OPERATIONxe2x80x9d.
U.S. Pat. No. 6,005,745 application Ser. No. 09/121,816, entitled xe2x80x9cCARTRIDGE LIBRARY WITH ENTRY/EXIT PORT AND METHOD OF OPERATION THEREOFxe2x80x9d.
U.S. Pat. No. 6,239,941, entitled xe2x80x9cCARTRIDGE LIBRARY AND METHOD OF OPERATIONxe2x80x9d.
U.S. Pat. No. 6,144,521, entitled xe2x80x9cCARTRIDGE MAGAZINE AND LIBRARY EMPLOYING SAMExe2x80x9d.
U.S. patent application Ser. No. 09/121,817, entitled xe2x80x9cDRIVE CARRIER AND CARTRIDGE LIBRARY EMPLOYING SAMExe2x80x9d.
U.S. patent application Ser. No. 09/708,433, entitled xe2x80x9cCARTRIDGE LIBRARYxe2x80x9d.
U.S. patent application Ser. No. 09/708,432, entitled xe2x80x9cCARTRIDGE PICKER ROBOT WITH RIBBON CABLE FOR CARTRIDGE LIBRARYxe2x80x9d.
U.S. patent application Ser. No. 09/708,451, entitled xe2x80x9cADJUSTABLE MOUNTING FOR BARCODE READER WITH BACKLASH PREVENTIONxe2x80x9d.
U.S. Design patent application Ser. No. 29/132,408, entitled xe2x80x9cCARTRIDGE LIBRARIESxe2x80x9d.
U.S. Design patent application Ser. No. 29/132,407, entitled xe2x80x9cCARTRIDGE MAGAZINExe2x80x9d.
In an automated tape library, one of the important tasks is to closely align the tape handling mechanism (the gripper) to tape cartridge storage cells ill the library and to tape drive openings. This is important because misalignment can make picking and placing tapes difficult and error prone.
Various means and techniques have been employed to accomplish proper alignment. Most of these techniques involve use of optical sensors. For example, a first common technique is to shine a light at a target associated to the cartridge location and sense the location of the reflection. A second common technique is to shine a light through an stationary aperture associated to the cartridge position and sense the location of the transmitted light.
The problem with the first technique is that the light source and the detector must be aimed to converge at a certain depth. If this depth cannot be controlled accurately, the axes converge in front of or behind the reflective surface. Also, the convergence of the optical axes cause parallax which confuses lateral position with depth.
A problem with the second technique is that supporting an emitter or detector on the side of the aperture opposite the robot and having it move with the robot is difficult.
What is needed, therefore, and an object of the present invention, is a calibration cartridge and technique of usage thereof (e.g., in an automated cartridge library) which facilitates calibration of locations in the automated cartridge library.
A calibration cartridge for an automated media library comprises a cartridge case having a calibration surface and an electromagnetic transmissive channel. The electromagnetic transmissive channel transmits electromagnetic radiation incident upon the calibration surface at a radiation reception port in a first position of the calibration cartridge so that the electromagnetic radiation travels interiorily through the calibration case and exits from the calibration cartridge at a radiation exit aperture in a second position on the calibration surface. The electromagnetic transmissive channel is preferably an electromagnetic conductor, such as an optical fiber or light pipe, for example.
The electromagnetic transmissive channel is situated in an interior of the cartridge case. The electromagnetic transmissive channel has a first end which terminates at the first position (e.g., the radiation reception port) on the calibration surface and a second end which directs electromagnetic radiation transmitted by the electromagnetic transmissive channel to the second position (e.g., the radiation exit aperture) on the calibration surface. In one example embodiment, the second end of the electromagnetic transmissive channel terminates interiorily in the cartridge case and directs the electromagnetic radiation toward the radiation exit aperture.
The calibration cartridge is usable in an automated information storage library which comprises plural cartridge-accommodating cells and a drive. Each of the plural cells is adapted to accommodate a media cartridge, the media cartridge containing an information storage media (e.g., magnetic tape). The drive transduces information with respect to the information storage media of a selected media cartridge inserted into the drive. The calibration cartridge is transportable by a cartridge transport system of the library for insertion into one of the plural cells and the drive.
The cartridge transport system comprises a cartridge gripper which selectively inserts the calibration cartridge into a calibration position in one of the plural cells and the drive, The cartridge gripper has an electromagnetic emitter and an electromagnetic detector. The electromagnetic emitter of the cartridge gripper is positioned to be essentially aligned with the radiation reception port of the calibration cartridge when the calibration cartridge is in the calibration position, and the cartridge gripper is proximate the calibration position. The electromagnetic detector of the cartridge gripper is proximate the radiation exit aperture of the calibration cartridge when the calibration cartridge is in the calibration position, but whether the electromagnetic radiation emitted from the radiation exit aperture of the calibration cartridge reaches the detector depends on a position of the cartridge gripper relative to calibration cartridge as the cartridge gripper is moved through a range of positions along differing directions or axes of movement.
In an illustrated embodiment, the radiation exit aperture is a quadrilateral-shaped aperture (e.g., a rectangular aperture). As another aspect, a dispersion angle of the electromagnetic emitter has a predetermined relationship relative to the radiation exit aperture to ensure that at least a portion of a cone of electromagnetic radiation emitted from the emitter of the cartridge gripper is incident upon the radiation reception port of the calibration cartridge regardless of the extent of movement of cartridge gripper through the range of positions.
A method of operating (e.g., calibrating and/or inventorying) an automated information storage library comprises uses the cartridge gripper to transport the calibration cartridge to a calibration position whereat the calibration cartridge is inserted into one of a cartridge-accommodating cell of the library, a calibration cartridge storage cell, and the drive. The cartridge gripper emits electromagnetic radiation incident upon the calibration cartridge which occupies the calibration position. The electromagnetic radiation emitted from the cartridge gripper is transmitted through an interior portion of the calibration cartridge to the radiation exit aperture of the calibration cartridge. Any electromagnetic radiation exiting from the radiation exit aperture of the calibration cartridge is used (e.g., detected) to ascertain a spatial description of the calibration position (e.g., spatial coordinates of the calibration position).
In determining the spatial description of the calibration position, the cartridge gripper while emitting the electromagnetic radiation is translated in a first direction and then in a second direction proximate the calibration cartridge. The electromagnetic radiation emitted from the emitter of the cartridge gripper is incident upon a radiation reception port of the calibration cartridge, so that the electromagnetic radiation can be conducted through the electromagnetic transmissive channel to the radiation exit aperture. Detection by the detector of the cartridge gripper of emission transitions from the radiation exit aperture of the calibration cartridge while the cartridge gripper moves along the first direction enables location of a first direction coordinate of a center of the radiation exit aperture. Similarly, detection by the detector of the cartridge gripper of emission transitions from the radiation exit aperture of calibration cartridge while the cartridge gripper moves along the second direction enables location of a second direction coordinate of a center of the radiation exit aperture. The electromagnetic radiation is emitted from the cartridge gripper with a sufficiently large dispersion angle whereby the radiation reception port of the calibration cartridge remains irradiated as the cartridge gripper is translated through a range of positions in the first direction. At some position in the range the detector of the cartridge gripper receives electromagnetic radiation emitted from the radiation exit aperture of the calibration cartridge and at other positions of the range the detector does not receive the electromagnetic radiation emitted from the radiation exit aperture of the calibration cartridge.